1. Field of the Invention
This invention relates to an improved method of stress rolling a metallic rim and, more specifically, one which will enhance the compressive stresses created in the rim during stress rolling.
2. Description of the Prior Art
It is well known that metallic rims of vehicle wheels or the like can be stress rolled to enhance the fatigue life of the rim which is being subjected to cyclical tensile stresses. Generally, this is accomplished by applying a compressive force to the rim in the portion thereof to be strengthened in a direction which is generally perpendicular to the direction of the tensile stresses produced therein. The application of the compressive force in this area will produce a compressive stress within the portion of the rim which is in the opposite direction to the eventual tensile stress. It has been found that "pre-stressing" in this manner enhances the fatigue life of such a rim which, during normal use, is expected to be repeatedly subjected to cyclical tensile forces. As a result, there remains a need for any method which might improve the efficiency and reliability of stress rolling.